1. Field of the Invention
This invention relates to a lagged type solenoid, and more particularly to a lagged type solenoid adapted to carry out one of its plunger advancing operation and plunger retreating operation at a low speed.
2. Description of the Prior Art
Conventionally, a solenoid has been extensively used to move a machine part or the like within a predetermined range.
The conventional solenoid used for this purpose includes a plunger slidably fitted in a coil bobbin having a magnetic coil wound on an outer periphery thereof in a manner to be movable in an axial direction thereof. The plunger is adapted to be advanced in the coil bobbin when the magnetic coil is excited.
In the conventional solenoid constructed as described above, its plunger advancing operation is carried out in such a manner that it is rapidly accelerated immediately after start of the operation, resulting in instantaneously reaching its stroke end.
The plunger retreating operation for returning the plunger to its original position is instantaneously carried out through a return spring by turning off the magnetic coil for its non-excitation.
Accordingly, when it is desired to instantaneously actuate a machine part or the like, the conventional solenoid is effectively used because the plunger is rapidly moved. However, the conventional solenoid fails to actuate the machine part slowly or at a constant speed.
For example, the conventional solenoid is used for a pachinko or pinball game installed in an amusement place or the like in such a manner to slowly actuate a so-called tulip element for operating a hole formed on a board of the pachinko. For this purpose, the solenoid employs a mechanism which is adapted to reduce driving force of a motor through a gear mechanism or the like and then transmit it to tulip actuating means. Unfortunately, such a mechanism is complicated in structure to a degree sufficient to substantially increase a size of the pachinko as well as its cost, resulting in a large area being required to install the pachinko.
Further, positional control of the conventional solenoid is carried out at only two positions or its advanced and retreated positions, so that it is impossible to stop it in the middle of its stroke, particularly, during the plunger advancing operation.
Moreover, in the conventional solenoid, when it is desired to hold the plunger at its stroke end during the plunger advancing operation, it is required to keep the magnetic coil turned on to continue excitation of the magnetic coil, resulting in attracting the plunger to the magnetic coil. This causes power consumption of the magnetic coil to be substantially increased.
Accordingly, it would be highly desirable to develop a lagged type solenoid which is capable of carrying out one of the plunger advancing operation and plunger retreating operation slowly or at a low speed.